DE2919595A1 - HELICOPTER ROTOR - Google Patents

Description

Dipl.-Ing. A. Wasmeier

Dipl.-Ing. H. Graf

Patent attorneys P.O. Box 382 8400 Regensburg 1

2 «ς nt D-8400 REGENSBURG 1 To the
German Patent Office GREFLINGER STRASSE 7
Telephone (0941) 5 4753 8 Munich / Telegram Begpatent Rgb.
: on / A kw <f] fg Telex 6 5709 repat d

Your sign Your Ref.

Your message Your letter

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W / p 9910

S ^a _a ? _e May 15, 1979 W / He

Applicant: 'WESTLAED AIRCRAi ¹ T ^ LIMITED Yeovil, Somerset, England

Title: "Helicopter rotor"

Priority: Great Britain No. 20226/78 of May 17, 1978

130018/0003

Accounts: Bayerische Vereinsbank (BLZ 75020073) 5 839 300 Postscheck München 89369-801

Place of jurisdiction Regensburc

May 15, 1979 w / Be / f- "_ W / p 9910

"Helicopter rotor"

Summary:

A helicopter profcor has a rotor head that is designed in this way is that it has a plurality of rotor blades which rotate about an axis. The rotor head has a hollow construction, and Each rotor blade is supported by an elastomeric bearing, the blade flapping, blade pivoting and blade angle adjustment movements can perform. A resilient support device is received within the rotor head structure and is each The rotor blade is assigned in such a way that a controlled limitation of the Eoljor blade movements in the blade flapping plane is achieved. at In the particular embodiment of the invention, the support device has interconnected inner and outer elastomeric elements Arrangements, the outer arrangement with each rotor blade via a common elastomeric blade swing damping device is connected, which results in a damping of the leaf pivoting movements between the leaves. The outer elastomeric arrangement results an automatic sheet slack stop.

The control response and maneuverability of a helicopter are influenced by the control movements generated by the rotor by flapping movements of each rotor blade. The control torques are determined by the pitch hinge displacement, i.e. by the value by which a pitch hinge extends the axis of rotation is offset; in general, the control torques due to the increased torque generated at the rotor head the larger the displacement, the higher.

Articulated rotor heads are known in which the rotor blade flapping, -swivel and angle adjustment movements can be achieved by mechanical joints that have ball or roller bearings. Such

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Rotor heads are large and complex, and have a high aerodynamic properties Resistance during operation and make frequent maintenance and care due to the extremely high levels that occur Centrifugal loads, the necessary continuous small rotational movements and the need for mechanical joint lubrication. Such rotor heads get wide " complicated by the fact that swing dampers are necessary to prevent fundamental resonance problems, and in some Power-driven leaf folding mechanisms are required in cases

It follows that the enlargement of the leaf flap displacement in such a rotor head the difficulty is further increased by the construction of the rotor head and that of the control system become more complicated, which leads to a larger and heavier rotor head, which absorbs the resistive loads acting during operation elevated.

It is already known that such mechanical bearings can be replaced by elastomer * To replace bearings in which rotor blade flapping and swiveling movements by moving around a common center of the bearing. Such elastomeric bearings can also be designed so that they result in blade angle adjustment movements and are able to do so to absorb the high centrifugal loads that during operation: bes occur in a helicopter rotor.

The use of elastomeric bearings instead of mechanical ones Storage has simplified the construction of articulated rotors in that it is then possible to perform all the required movements in one single bearing unit are included, which does not require lubrication, so that maintenance and repair costs are significantly reduced will. However, the problem has not been solved that necessarily increases the dimensions, especially the overall diameter of the rotor head when it is necessary to improve the control response in a particular case, since it it is still necessary for this purpose to move the bearing and thus the bearing center further outwards in order to offset the flapping hinge to enlarge. This in turn results in a corresponding increase in the length of a control route to the

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Incline control lever and / or the dimensions of an actuator, e.g. a swash plate or a turnstile operating mechanism.

According to the invention there is an L-helicopter rotor with a rotor head proposed, which is designed so that it receives a plurality of rotor blades that are rotatable about an approximately vertical axis are; The rotor head has an elastomeric bearing for each rotor blade, the blade flapping, blade pivoting and blade angle adjustment movements also allows a sheet swivel damping device and a resilient support which is designed so that it is a controlled limitation of rotor blade movement in the leaf flap plane results.

In a particular embodiment of the invention, this is elastomeric Bearings are hollow, and a spindle extends within the hollow bearing and extends inward where it attaches to one inner end attached to the shock absorber device. Appropriately, the spindle is designed so that it protrudes outwardly from the bearing and in an outer end that is designed for attachment to the rotor blade, ends.

The inner end of the spindle can accommodate a ball bearing, which with the shock absorption device is connected. Preferential prices can do that Bearings perform an axial sliding movement on the spindle, allowing for blade flapping and pivoting movements during operation can worry.

Preferably the blade swing damping device is an elastomeric one Damping device which has at least one layer of an elastomeric material for each rotor blade, which is located in the pivot plane of the assigned rotor blade is extended and designed in such a way that that it is working on overshoot during blade pivoting movements. The elastomeric layers can be positioned between mutually facing, offset surfaces of individual support components that are received by the ball bearings, and a device

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ORIGINAL INSPECTED

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connected "or glued to the construction of the rotor head is supported and which each of the elasfcomeren layers has in common is, so that a pivot damping between the sheets is achieved.

The individual support components expediently have a component with an I-cross section and it is an elastomeric layer bonded between each of the opposing surfaces and the surfaces of the common support device

The common support device preferably has upper and lower annular plates that are connected to one another by approximately tubular component connected by a ball bearing is recorded, which has a geometric center on the axis of rotation of the rotor head; the camp is from the rotor head construction on gemomen so that it is able to perform axial sliding movements relative to the construction for collective blade flapping movements. This is expedient centering bearing is a ball bearing that attaches to a spindle i-st, which protrudes in the axial direction inward from a cover plate attached to the rotor head.

The lower annular plate has, for example, a downwardly directed skirt portion that coincides with the resilient Support device is attached.

The support device has in one embodiment of the invention an annular outer elastomeric assembly and an inner elastomeric assembly; one the circumference of the outer elastomer The arrangement of the supporting flange is connected to a lower end of the edging part. The outer elastomeric assembly is arranged concentrically to the axis of rotation and preferably has alternating layers of elastomeric and metal shims which are arranged parallel to -r axis of rotation. The outer arrangement is, for example, the inside through a tubular component supported, which is formed concentric to the axis of rotation and

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COPY

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attached between upper and lower oval-shaped endplates is, the upper and lower! 'laugh of a ring-shaped pile is connected or glued by alternating layers of elastomeric and metal shims that form the inner elastomeric assembly form.

In one embodiment of the invention, the alternating layers of the internal arrangement can be in a plane approximately perpendicular to the Eotationsach.se be oriented, and an annular intermediate met all plate have a radially inwardly extending Has flange that is grounded to the rotor head assembly. The inwardly running splash is expediently in the Fehead attached to an upper end of a tubular member which extends upwardly into the interior of the inner elastomeric assembly of a lower end that attaches to the rotor head structure is. Preferably the stack is precompressed between the upper and lower end plates.

In a further embodiment of the invention, a helicopter rotor is used proposed with a rotor head which is designed so that it has a plurality of rotor blades rotatable about an approximately vertical Axis accommodates; the rotor head points to each rotor blade a hollow elastomeric bearing that matches the rotor head construction is attached so that flapping, pivoting and angular adjustment movements of the associated rotor blade are possible; there is also a spindle rigidly set by the hollow bearing and is available from there for attachment with the rotor blade facing outwards; Furthermore, an elastically yielding support device is provided which is a controlled one Limitation of blade flapping movements results, and one having an annular outer elastomeric assembly and an inner elastomeric assembly, the outer assembly having an inner bath associated with the spindle protruding radially inward from the elastomeric bearing, while the inner assembly is grounded to the rotor head construction.

The invention is explained below in conjunction with the drawing an exemplary embodiment explained. Show it:

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COPY

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Fig. 1 is a partially sectioned side view of a Helicopter rotor according to the invention,

FIG. 2 is a view along the section line X-X of FIG. 1, and FIG. 3 is a sectional view along the section line Y-Y of FIG.

A helicopter rotor has a rotor head 11 and is designed so that it accommodates four rotor blades (not shown) which are rotatable about a vertical axis 12. The rotor head 11 has a hollow construction 13 with an open upper end which is closed by a detachable cover plate 14- secured by screws is fixed.

Each rotor blade has an outer end of a spindle 15 (in Only one of these is shown in FIG. 1, which extends inwardly into the rotor head 11. The spindle 15 is hollow elastomeric bearing assembly 16 attached, which is connected to the structure 13, and protrudes inwardly from where it is an inner end slidably disposed in a ball bearing 17 is, concludes.

The bearing assembly 16 has a conical and a part-spherical one elastomeric bearing, each of which consists of a composite arrangement of alternating layers of elastomeric and metal shims. The conical and part-spherical bearings are arranged around a geometric center point 18 and are in operation enables the bearing arrangement 16 rotor blade flapping, pivoting and -angle adjustment movements. The bearing 16 is of the rotor head structure 13 attached so that there is each spindle 15 and the associated Rotor blades with a preselected cone angle ^ - recorded will.

Each ball bearing 17 connects the corresponding spindle 15 to a sheet swivel damping device 19 and takes an approximately horizontal one Support component 20 with I-cross section (Figures 1 and 3); the components 20 are in the case of a four-bladed rotor of the embodiment shown in an approximately rectangular scheme

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arranged, which surrounds the axis of rotation 12. Upper and lower annular rectangular sheets 21 and 22, each of which has a has circular central opening, are received at a distance from opposite surfaces of the support members 20, and Layers of elastomer 25 are connected or connected between adjacent surfaces of the support components 20 and flats 21 and 22. glued, the position of the layers 23 being dashed in FIG. 2 shown as extended in a plane which coincides with a pivot plane of the movement of the zugeox ^ dneten spindle 15.

The plates 21 and 22 therefore connect the respective layers of the elastomer 23 so that a cushioning between the sheets is achieved, and result in the support device of the damping device 19 from the rotor head structure through an inner one tubular component 24- supported by an elastomeric centering ball bearing 25 is recorded. The bearing 25 has a geometric center 26, which is arranged on the uotationsach.se 12, and is displaceable in the axial direction on a spindle 27 which protrudes from the cover plate 15 inward. The elastomeric bearing 25 forms a Yerbund arrangement of alternating layers of etomeric and metal shims.

A downwardly directed skirt portion 28 is integral therewith of the lower plate 22 and is used to provide the damping device 19 with a resilient rotor blade support device 29 to connect, and consists of an annular outer elastomeric assembly 30 and an annular inner elastomeric assembly 31.

A lower flanged end of the skirt portion 28 is attached to a flange 32 formed on a peripheral support of the outer assembly 30 which has alternating layers of elastomeric wad. Has Metallbexlagen which are arranged concentrically and parallel to the axis of rotation 12. The outer arrangement 30 is internally supported by an approximately tubular component 33 which is attached concentrically to the axis 12 and between

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upper and lower annular end plates 34 and 35 is attached. The inner assembly 31 consists of a stack of alternating Layers of elastomeric and metal shims disposed between end plates 34 and 35; the layers are concentrated risch to the axis 12 and oriented in a plane approximately perpendicular to the axis 12. An intermediate metal plate 36 is integral in connected or glued to the stack.

The inner elastomeric assembly 31 is between the end plates 3 ^ and 35 pre-compressed by a plurality of bolts so that the assembly is pre-loaded, and one radially inward extending flange of the intermediate plate 36 is with the rotor head construction 13 grounded by a tubular member 37, which is shown in the interior of the assembly 3I from a lower one, with the construction 13 connected end extends upwards. The pre-compression of the arrangement 31 is sufficient to prevent tension in the Layering of the elastomer occurs during axial movements of the end plates 34 and 35 due to blade flapping movements.

A pitch control arm 38 (Figures 1 and 2) is rotatable with each Spindle 15 attached and connected to the inside end of bearing assembly 16; arms 38 have downward control rods 39, which are guided through slots (not shown) in the lower wall of the structure I3, where they connect stand with the helicopter flight controls.

When operating a rotor according to the invention, rotor blade flapping, -swivel and angle adjustment movements on the spindle transmitted and permitted by the elastomeric bearing assembly 16. Pivoting movements of the rotor blade are made possible by the elastomer Layers 23 of the swing damping device 19, which are on shear The layers 23 are preferably made up Made of synthetic rubber due to its high hysteresis properties, which result in the necessary damping properties in this level.

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The damping arrangement according to the invention ensures that a Damping occurs between the sheets, so that the damping device is not caused by large lagging movements lying in the plane of the sheet of the leaves can be influenced, whereby the size and weight of the damping device 19 can be kept small. The bearing 25 centering the damping device eliminates disadvantageous ones Blade bending movements that occur when the rotor is started and when braking; this means that the damping device no low-frequency deflections of the rotor blades that occur during these phases of operation need to absorb. This simplifies the design of the damping device and ensures that optimum damping properties are obtained at a given rotor operating speed can be achieved.

An identical upward flapping movement for all of them Rotor blades, which is caused by a collective pitch motion, are caused by deflection of the annular outer elastomeric Arrangement $ 0 of the support device 29 caused and is achieved by a shearing motion between alternating layers of the assembly. Similarly, the limitation results in that provided by the annular outer elastomeric assembly 30 a slack stop for the rotor blade when the rotor is at rest.

Cyclical flapping movements of the rotor blades, which result from a cyclical pitch setting of the controls, will be possible through the annular outer elastomeric arrangement 30 and are on the annular inner elastomeric assembly 31 of the support device 29, causing the stack of alternating layers of elastomeric and metal shims to be sheared will. As already mentioned, the elastomeric layers are the inner elastomeric assembly 31 free from tensile stresses during such blade flapping movements due to the precompression the arrangement ο

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The automatic limitation of the blade flapping movements in the cyclical: Operation provided by the annular inner elastomeric assembly 31 is achieved, is used to build a virtual or effective flapping hinge position, the outside with respect to an actually Is the hinge position determined by the geometric center 18 of the elastomeric bearing assembly 16 that receives each rotor blade, is defined. The invention thus enables one to be enlarged Blade hinge displacement position effective without physically increasing the dimension between axis 12 and the bearing center point 18 is achieved, whereby a compact rotor head is achieved, de: gives an improved control response. On the other hand, if the Flapping joint displacement of an existing rotor results in sufficient control behavior, the invention allows the reduction of the entire dimension of the rotor head by the actual flapping hinge displacement position without adversely affecting the control: response properties is reduced.

For example, in a practical embodiment of the invention a special helicopter has an actual flapping joint · displacement of 5% of the blade radius, measured from the axis of rotation and a virtual or effective flapping hinge displacement position of 9%) which increases the control response of the rotor and maneuverability of the helicopter can be improved without increasing the overall diameter of the rotor head.

This results in a compact design, reducing weight and being more aerodynamic Resistance can be reduced and the control system simplified Furthermore, the inside of the arrangement of the control arms 38 is special; expedient when used in a helicopter with a hollow gear box, since the control rod 39 with the control device v < can be bound, which is arranged within the hollow gear box, thereby further simplifying the control device and can be protected and a reduction in both weight! the size dimensions is achieved.

COPY

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The present invention also allows for the selection of any desired The stiffness ratio between the flapping and pivoting planes of the movement for the adaptation to special applications is essential I simplified.

The extensive use of elastomer material in the bearings and the support device according to the invention results in a wide range Simplification and reduction; the maintenance and repair costs. · This effort is further reduced by using a hollow rotor head construction, in which the ropes required for operation are picked up, preventing the ingress of dirt Moisture is turned off. The hollow construction makes it easier also the design of an aerodynamically clean rotor head in order to keep the air resistance as low as possible during operation.

An embodiment of the invention has been described above shown, but the invention is not limited thereto. For example, the annular upper and lower support plates 21 and 22 of the shock absorbing device 19 have other suitable shapes, determined by the number of existing on the rotor head Rotor blades are intended. Ss can have more than two layers elastomeric material 23 be assigned to each spindle 15, whereby 'increases the connected surface area and consequently the Damping properties improve vir earths. The inner elastomeric arrangement 31 of the support device 29 can be part-spherical and can be concentric about the geometric axis 26 of the bearing 25 be arranged, which receives the swivel damping device 19. On the other hand, the separate elastomeric stack that forms the inner having elastomeric arrangement 31, extends over the entire enclosed Surface, the intermediate plate 36 with the construction 13 is grounded through a plurality of posts positioned through openings in the stacks. This creates the connected surface and thus increases the control force, which reduces the overall height of the resilient support device 29 and, consequently, of the Total height of the rotor head 11 can result. The elastomeric centering bearing 25 can be replaced by another form of ball bearing. Depending on the design features of a rotor head and

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The control rods can screw the gear box at a "certain stroke" 39 actuated by a corresponding control device " e.g. by an internally mounted turnstile mechanism or by an external swash plate mechanism.

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Claims (1)

_ ■ ;. 5.1979 w / He -Ζ'- _ν . . Λ / ρ 9910 2319595 head assembly (13) is grounded. 6. Rotor according to claim 5, characterized in that the radial inward splash near an upper end of a ■ tubular component (37) '"is attached and up into the Inner .der inner elastomeric assembly (31) from a lower End that is attached to the rotor head assembly (30) extends. 7. Rotor according to one of claims 4 to 6, characterized in that the stack of alternating layers of elastomeric and j- metal shims is pre-compressed between the upper and lower plates (34, 35). 8. Rotor according to one of claims 2 to 7 »characterized in that that a flanged part (32) which extends the circumference of the outer elasto- _ meren arrangement (31) receives, with a Blattschvrenkdämpfungsvorrichtung (19) is attached. 9. Rotor according to claim 8, characterized in that the blade swing damping device (19) for jed.es rotor blade at least, _ _{r has} a layer of elastomer (25) which is extended in the pivot plane of the associated rotor blade and which is designed so that it is subjected to shear during the blade pivoting movements. 10. Rotor according to claim 9 _5, characterized in that the layers of the elastomer (23) are connected between facing, offset surfaces of individual support members (20) which are attached to an inner end of a spindle (15) which extends through a hollow center of the elastomer bearing (16) extends for attachment to a rotor blade, and that each of the layers of the elastomer (23) has a support device (21, 22) in common. 11. Rotor according to claim 10, characterized in that the individual Support components each have a component (20) with an I cross-section have, which is received by a ball bearing (17) which slides in the axial direction on the inner end of the spindle (15) 130018/0003 ORIGINAL INSPECTED COPY May 15, 1979 W / He - 2 ~ - _v ... ¥ / p 9910 head assembly (13) is earthed. 6. Rotor after. Claim 5, characterized in that the radial inward splash near an upper ead of one tubular member (37) "is attached and up into the Innen.der inner elastomeric assembly (31) from a lower End attached to the rotor head assembly (30) extends. -7 · Rotor according to one of claims M- to 6, characterized in that the stack of alternating layers of elastomer and j- metal inserts between the upper and lower plates (34-, 35) is pre-compressed. 8. Rotor according to one of claims 2 to 7, characterized in that that a flanged part (32) which surrounds the periphery of the outer elastomer Arrangement (31) receives, with a blade swing damping device (19) is attached. 9. Rotor according to claim 8, characterized in that the blade swing damping device (19) for each rotor blade at least _; ^ has a layer of elastomer (23) which is extended in the pivot plane of the associated rotor blade and which is designed so that it is subjected to shear during the blade pivoting movements. 10. Rotor according to claim 9 »characterized in that the layers of the elastomer (23) are connected between facing, offset surfaces of individual support components (20) which are attached to an inner end of a spindle (15) which extends through a hollow center of the elastomeric bearing (16) for attachment extends on a rotor blade, and that each of the layers of the elastomer (23) has a support device (21, 22) in common. 11. Rotor according to claim 10, characterized in that the individual Support components each have a component (20) with an I cross-section have, which is received by a ball bearing (17) which slides in the axial direction on the inner end of the spindle (15) 130018/0003 _COPY ORIGINAL INSPECTED ^ May 15, 1979 W / He - 3 - "· - V / p 9910 is arranged, and that a layer of elastomer (23) between each of the opposing surfaces and surfaces of the common Support device (21, 22) is connected. 12. Rotor according to claim 11, characterized in that the common Support device has upper and lower annular plates (21, 22) which are connected to one another by a tubular component (2 * 0) are, which is arranged by a ball bearing (25) with a geometric center (26) on the axis of rotation (12) is, aujgaiaimen where the bearing (25) from the rotor head assembly (IJ) is received so that it can perform axial sliding movements relative to the assembly (15). 13. Rotor according to claim 12, characterized in that the lower annular plate (22) has a downwardly extending skirt portion (28) which mates with the flanged portion (32) of the outer elastomeric Arrangement (30) is attached. COPY 130018/0003 ORIGINAL INSPECTED